Safár J, Simková H, Kubaláková M, Cíhalíková J, Suchánková P, Bartos J, Dolezel J
Laboratory of Molecular Cytogenetics and Cytometry, Institute of Experimental Botany, Olomouc, Czech Republic.
Cytogenet Genome Res. 2010 Jul;129(1-3):211-23. doi: 10.1159/000313072. Epub 2010 May 26.
The large bread wheat genome (1C approximately 17 Gbp) contains a preponderance of repetitive DNA and the species is polyploid. These characteristics together serve to hamper the molecular analysis of the wheat genome. Its complexity can, however, be reduced by using flow cytometry to isolate individual chromosomes, and these can be exploited to construct chromosome-specific BAC libraries. Such libraries simplify the task of physical map construction, positional cloning and the targeted development of genetic markers. Rapid improvements in the efficiency and cost of DNA sequencing provide an opportunity to contemplate sequencing the wheat genome by preparing sequence-ready physical maps for each chromosome or chromosome arm in turn. The quality of the chromosome-specific libraries depends on their chromosome coverage and the mean insert size. First-generation libraries suffered from a relatively low mean insert size, but improvements to the protocol have generated a second wave of libraries with a significantly increased mean insert size and better chromosome coverage. Each chromosome (arm)-specific library is composed of a manageable number of clones, and so represents a practical tool in the area of wheat genomics.
普通小麦的基因组很大（1C约为17 Gbp），富含重复DNA，且该物种为多倍体。这些特征共同阻碍了小麦基因组的分子分析。然而，通过流式细胞术分离单个染色体可以降低其复杂性，利用这些染色体可以构建染色体特异性BAC文库。此类文库简化了物理图谱构建、定位克隆以及遗传标记靶向开发的任务。DNA测序效率和成本的快速提高为通过依次为每条染色体或染色体臂制备序列就绪的物理图谱来考虑对小麦基因组进行测序提供了契机。染色体特异性文库的质量取决于其染色体覆盖率和平均插入片段大小。第一代文库的平均插入片段大小相对较低，但实验方案的改进产生了第二代文库，其平均插入片段大小显著增加，染色体覆盖率也更高。每个染色体（臂）特异性文库由数量可控的克隆组成，因此是小麦基因组学领域的实用工具。
